1. Field of the Invention
The present invention relates to an electronic musical instrument capable of producing a musical waveform by repetitively reading out a waveform segment in a loop from among the stored continuous musical waveform in a data format.
2. Description of the Prior Art
Among the currently prevailing music, there is a style of music in which a memorized musical phrase is repeatedly used to construct a length of music performance. Such a musical performance is formed by firstly designating a loop segment which is a waveform segment within a continuous waveform recorded and stored in the instrument and which constitutes a musical phrase to be repeatedly used in a loop, and secondly reading out the designated loop segment repeatedly to form a longer waveform for a musical performance.
And in order to superimpose the loop segment (loop phrase) on to an object phrase such as a phrase in another musical performance and a phrase in an automatic musical performance, the prior art procedure has employed the following steps:
1) previously determining a tempo for the loop phrase by calculation at human end, PA1 2) measuring the tempo of the object phrase, and PA1 3) compressing/expanding the time axis (time scale) of the loop phrase in accordance with the ratio between the tempo of the loop phrase and the tempo of the object phrase.
In the above-mentioned prior art procedure, however, the tempo for reading out the loop phrase should necessarily be designated previously with respect to the recorded (prepared) loop phrase, in order to compress/expand the time axis of the loop phrase in accordance with the tempo of the object phrase on which the loop phrase is to be superimposed. This procedure has been elaborate and time-consuming.
Moreover, the loop phrase should be divided into several sub-phrases for compressing/expanding the time axis, and for this purpose the user of the instrument was to designate the dividing number. But when the arbitrarily designated dividing number was inadequate, the time-axis compressed or expanded waveform might exhibit unnatural beats relative to the number of meter beats of the recorded phrase.
Furthermore, in the prior art time-axis compression/expansion technology, the compression/expansion ratio was controlled per phrase, and therefore portional control of such a ratio within a phrase was not heretofore possible. To this end, it was not possible to introduce in a phrase such a portional fluctuation of rhythm as would be caused by portionally controlling the compression/expansion ratio in a phrase.